In a conventional cellular system, whatever generation is considered, a base station has at least two interfaces, an air interface to mobile user equipment (UE) and a backhaul interface to the core network.
In a cellular network, the backhaul portion of the network comprises the intermediate links between the core network, or backbone, of the cellular network and the small subnetworks at the “edge” of the entire cellular network. For example, while mobile user equipments communicating with a single base station constitute a local subnetwork, the connection between the base station and the rest of the world begins with a backhaul link to the core network of cellular network.
With more and more expectations coming from mobile user equipments, with respect to geographical coverage, available bandwidth, and quality of service level, that is to say with a continuous increase in user demand, traditional backhaul can be easily overloaded, thereby creating a backhaul bottleneck because of insufficient backhaul capacities.
A solution that could strike one's mind is to increase backhaul capacities in a limitless way in order to meet user's demand increase. But upgrading network infrastructure rapidly raises capital and operational expenditures to a non acceptable level for telecommunication operators.
In a first prior art, for example described in English application GB 2454872, a solution to this problem is proposed. When backhaul traffic load becomes too high, corresponding base station of the network merely refuses new entering calls and a handover to a neighbor base station of the same network is managed. A new link is set up between new neighbor base station and mobile user equipment. This can only be done when there is at least one neighbor base station available in the network.